ICgrep is a very fast regular expression search program, particularly for complex regular expressions, supporting standard egrep syntax, except for Posix character classes. It supports searches using ASCII or UTF-8; Unicode two letter classes are supported. The most receent development version of the ICgrep source code is available in the Parabix software repository, along with instructions necessary to build the software on a wide range of platforms. The full source code can be obtained by running the following command in the command line.